GCr15轴承钢摩擦副的表面胶合失效研究

Scuffing Failure Investigation of GCr15 Bearing Steel Friction Pairs

表面胶合失效是高速重载条件下滑动摩擦副的重要失效形式，尽管人们已对其进行了不少研究，然而不仅由于机理复杂，至今尚无公认的合理计算方法，而且由于试验条件和试验过程不同，有些试验结果是相互矛盾的。在影响表面胶合失效的诸多因素中，表面粗糙度和相对滑动速度都非常重要，因此，利用改装的ＭＨＫ５００型环。块磨损试验机在纯矿物油润滑下对ＧＣｒ１５轴承钢同材质摩擦副的表面胶合失效进行了试验研究，集中考察了表面粗糙度和相对滑动速度的影响，结果表明，摩擦副的抗胶合能力是随着相对滑动速度的提高而下降；摩擦副的表面粗糙度存在一个最佳值，其在此粗糙度下的抗胶合能力最强，而当提高或降低表面粗糙度时，摩擦副的抗胶合能力都下降。根据所获试验结果对文献报道的几种表面胶合失效理论模型的适用性作了详细分析，发现这些都不能解释本试验中所发生的各种胶合失效现象。因此，按照“发生塑性变形的微凸体之密度高到足以连成大片时就可能发生表面胶合失效”的设想，提出了一种新的表面胶合失效模型─—表面宏观塑变模型，认为表面胶合失效是摩擦副表面发生宏观塑性变形的结果．

Scuffing appears mainly in sliding contacts under high speed-heavy load conditions. Although scuffing has been investigated for many years,the cause of scuffing has th us far eludedour understanding and as a consequence, its prevention is not always successful,nor its occurencepredictable. Among the factors which have influence on scuffing failure,surface roughness and slidingspeed are very important.So,using a Timken machine,scuffing tests have been conducted onGCr15 bearing steel friction pairs lubricated with pure mineral oil and the effects of surfacetoughness and sliding speed on the scuffing behavior have been studied in detail in this paper.Theresults obtained indicate that the critical load of scuffing decreases with increasing of sliding speed,there is an optimum surface roughness which has highest scuffing resistant,the critical load at firstincreases with decreasing of surface roughness,passes through a maximum and finally decreases atvery smcoth sur face. Using the experimental data obtained in this paper,the validity of severalscuffing medels in literature have been analyzed,the results indicate that none of the models canexplain various scuffing behaviors observed in the tests of this paper.So,based on the idea thatscuffing will occur if plastically deforming asperities are spaced so closely that they coalesce to forma scuffing mark,a new seuffing medel-surface plastic flow has been formulated in this paper.Thismedel hypothesizes that scuffing failure is the results of surface plastic flow. It can explain variousscuffing behaviors observed in the tests of this paper.